/*
 * Copyright [2013-2021], Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.alibaba.polardbx.common.utils;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

public final class Pair<K, V> {

    private final K key;
    private final V value;

    @JsonCreator
    public Pair(
        @JsonProperty("key") K key,
        @JsonProperty("value") V value) {
        this.key = key;
        this.value = value;
    }

    @JsonProperty
    public K getKey() {
        return key;
    }

    @JsonProperty
    public V getValue() {
        return value;
    }

    public static <K, V> Pair<K, V> of(K key, V value) {
        return new Pair<>(key, value);
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("(").append(key).append(", ").append(value).append(")");
        return sb.toString();
    }

    private static final int HASH_CONST = 37;

    @Override
    public int hashCode() {
        int hash = 17;
        if (key == null) {
            hash += HASH_CONST;
        } else {
            hash = (hash << 5) + (hash << 1) + hash + key.hashCode();
        }
        if (value == null) {
            hash += HASH_CONST;
        } else {
            hash = (hash << 5) + (hash << 1) + hash + value.hashCode();
        }
        return hash;
    }

    @SuppressWarnings("rawtypes")
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof Pair)) {
            return false;
        }
        Pair that = (Pair) obj;
        return isEquals(this.key, that.key) && isEquals(this.value, that.value);
    }

    private boolean isEquals(Object o1, Object o2) {
        if (o1 == o2) {
            return true;
        }
        if (o1 == null) {
            return o2 == null;
        }
        return o1.equals(o2);
    }

}
